Maximum Efficiency Tracking Using Active Shunt Compensation in Single-Stage Inductive Power Transfer for Constant Power Battery Charging With High Voltage Gain

Constant power (CP) charging profile in inductive power transfer (IPT) systems offer significant advantages, such as reduced charging time and lower thermal requirements, compared to constant current charging. In addition, achieving a high voltage gain from a CP-IPT charger is essential for high voltage battery charging applications. However, improving efficiency in CP-IPT chargers operating at high voltage gain remains unexplored. In this article, we propose a novel load matching scheme for CP charging, which utilizes active shunt compensation on the secondary side to enhance efficiency at higher voltage gains. Furthermore, we analyze design considerations to ensure soft-switching operation. The steady-state characteristics of the proposed wireless charger topology are derived analytically, and the scheme is validated on a 150 W experimental setup. We also demonstrate the converter's protection during an open circuit fault on the load through experimental study. The proposed topology enables high-efficiency power transfer throughout the CP charging mode, making it particularly suitable for stationary charging applications of high voltage batteries.